From: tip-bot for Neeraj Upadhyay <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org,
peterz@infraded.org, mingo@kernel.org, neeraju@codeaurora.org
Subject: [tip:smp/urgent] cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
Date: Thu, 6 Sep 2018 06:51:51 -0700 [thread overview]
Message-ID: <tip-f8b7530aa0a1def79c93101216b5b17cf408a70a@git.kernel.org> (raw)
In-Reply-To: <1536126727-11629-1-git-send-email-neeraju@codeaurora.org>
Commit-ID: f8b7530aa0a1def79c93101216b5b17cf408a70a
Gitweb: https://git.kernel.org/tip/f8b7530aa0a1def79c93101216b5b17cf408a70a
Author: Neeraj Upadhyay <neeraju@codeaurora.org>
AuthorDate: Wed, 5 Sep 2018 11:22:07 +0530
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 6 Sep 2018 15:21:37 +0200
cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the
load of st->should_run to prevent reordering of the later load/stores
w.r.t. the load of st->should_run.
Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core")
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infraded.org>
Cc: josh@joshtriplett.org
Cc: peterz@infradead.org
Cc: jiangshanlai@gmail.com
Cc: dzickus@redhat.com
Cc: brendan.jackman@arm.com
Cc: malat@debian.org
Cc: mojha@codeaurora.org
Cc: sramana@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org
---
kernel/cpu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index aa7fe85ad62e..eb4041f78073 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -607,15 +607,15 @@ static void cpuhp_thread_fun(unsigned int cpu)
bool bringup = st->bringup;
enum cpuhp_state state;
+ if (WARN_ON_ONCE(!st->should_run))
+ return;
+
/*
* ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
* that if we see ->should_run we also see the rest of the state.
*/
smp_mb();
- if (WARN_ON_ONCE(!st->should_run))
- return;
-
cpuhp_lock_acquire(bringup);
if (st->single) {
prev parent reply other threads:[~2018-09-06 13:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-05 5:52 [PATCH] cpu/hotplug: Fix acquire of st->should_run in cpuhp_thread_fun() Neeraj Upadhyay
2018-09-05 8:12 ` Peter Zijlstra
2018-09-06 13:51 ` tip-bot for Neeraj Upadhyay [this message]
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